//系统函数
let num = parseInt('123');
console.log('num+1=' + (num + 1));//124
let num1 = parseInt('123.23');
console.log('num1+1=' + (num1 + 1));//124
let num2 = parseInt('123.23ss');
console.log('num2+1=' + (num2 + 1));//124
let num3 = parseInt('ss123.23');
console.log('num3=' + num3);
console.log('num3+1=' + (num3 + 1));//NaN

let num4 = parseInt('123.23');
console.log('num4+1=' + (num4 + 1));//124

let num5 = parseFloat('123.23');
console.log('num5+1=' + (num5 + 1));//124.23
let num6 = parseFloat('123.23ss');
console.log('num6+1=' + (num6 + 1));//124.23
let num7 = parseFloat('ss123.23');
console.log('num7+1=' + (num7 + 1));//NaN
let num8 = parseFloat('12');
console.log('num8+1=' + (num8 + 1));//13
let num9 = parseFloat('12');
console.log('num9+1=' + (num9 + 0.1));//12.1